1) Choices doesn’t support WooCommerce yet but Kriesi is thinking about an integration. I’ll ask him if there’s a final decision now.

2) It’s hard to say because Abundance is was created as dedicated shop theme. Thus it’s perfectly optimized for WooCommerce. However Propulsion offers more features like bbpress support and portfolio items and it’s responsive – compared to Abundance it’s imho the better theme because of the additional features. If Choices supports WooCommerce in the future it will be the best theme for WooCommerce because it offers more features than Propulsion + its design is imho better.

3) Magento is a dedicated shopping platform and can’t be compared to WP + WooCommerce + our themes. It depends on your requirements and experience. Magento works quite different compared to WordPress and it’s like comparing a racing car with a jeep – both will bring you from A to B but depending on the streets you’ll probably prefer one over the other…